The present invention is generally related to signal processing, and more specifically related to correlating signals from multiple arrays.
In a typical active sonar or radar system, acoustic/electromagnetic signals are transmitted through a medium (e.g., water for sonar, air for radar) toward a target area and acoustic/electromagnetic returns (e.g., echoes) from the target area are received by receiving elements (e.g., sensors) and processed for display. In a passive system, no signals are transmitted. Rather, energy radiating from the target area is processed for display. Typically, localization of a target of interest comprises determining the range and bearing to the target.
Of particular interest is the localization of a target utilizing multiple co-linear arrays. To improve performance, multiple co-linear arrays are combined to increase the system aperture, thus extending the near field. Conventional systems form beam patterns for each linear array. The system then cross-correlates the beam data between array pairs. The system then finds the magnitude squared of the complex correlation output, and this output is non-coherently processed to form a range/bearing surface.
A disadvantage of the above approach is that noise degrades the cross-correlation process, thus detrimentally affecting detection and localization performance. Thus, a need exists for a system and method for localizing a target utilizing multiple co-linear arrays, that does not suffer the herein-described performance degradation.
A system for localizing a target using a plurality of co-linear arrays of sensors includes a beamformer, a cross-correlator, a time delayer, and a summer. The beamformer forms respective beam pattern signals for each of the plurality of arrays. The cross-correlator coherently cross-correlates the beam pattern signals for providing respective correlogram signals. The time delayer time delays each correlogram signal in accordance with a respective expected time delay. And the summer coherently sums the time delayed correlogram signals for localizing the target.